In recent years extracapsular cataract extraction, wherein at least a part of the capusular tissue is left intact within the eye, has overtaken intracapsular extraction involving the removal of the crystaline lens together with its supporting capsular tissue. In one of the techniquesphacoemulsification, one of the specialized techniques which is utilized in extracapsular cataract extraction, a portion of the anterior lens capsule is removed but the remainder of the capsule remains in the course of this technique wherein ultrasonic energy is used to break up the lens nucleus which is then aspirated.
The advantages of phacoemulsification include a small incision whereby mechanical vibration transforms lens matter into an emulsion which can be aspirated from the capsular bag and replaced by infusion fluid. However, there are disadvantages in that there is a higher incidence of complications due to the fact that this specialized technique is difficult, the lens material is more likely to become mixed with vetreous, and the iris may become damaged. In addition, many nuclei are just too dense for comfortable phacoemulsification. Moreover, the equipment is expensive.
Another of the techniques used in extracapsular cataract extraction provides for bisecting a cataractous nucleus of an eye with a knife-like instrument pressed against a so-called solid vectis or microcutting board positioned behind the nucleus and then extracting the bisected nuclear portions through an incision providing access to the anterior eye chamber. However, this technique places a premium on precision symmetry in the bisecting of the nucleus core so as to ensure nuclear fragments of common size to enable one to minimize the length of the required incision which, obviously, must be of sufficient size to accommodate removal of the largest sized fragment.
Another technique used by a number of ophthalmologists is an extracapsular extraction method wherein a limbal incision is extended for about 160.degree. which permits the lens nucleus to be removed as a unit and the cortical material to be aspirated from the eye. With this type of extracapsular cataract extraction, the method is less complicated, for the technique is simpler than phacoemulsification, but the extensive wound requires longer time in healing, and longer convalescence and stabilization.
In each of these described methods, a "capsular bag" remains in place and becomes an ideal site for placement of intraocular lens (IOL) implant as fully described in my U.S. Pat. No. 4,932,967 dated Jun. 12, 1990 and entitled "Intraocular Lens Implant".